Functional Additive for Several Applications

The new additive is ideal for boosting fracture
toughness and resistance to micro-cracking

The functional additive is widely used by the aerospace industry for prepreg and resin-transfer molded carbon fiber-reinforced epoxy, is gaining ground in epoxy composites for automotive, and could be used for high-performance sporting goods as well. The material is produced by Sumitomo Chemical (Tokyo) and is sold in North America by Sumitomo Chemical Advanced Technologies, which will exhibit for the first time at the Composites & Advanced Materials Expo (CAMX).

It is offered pelletized for injection molding, extrusion, and film processes and in powder form for cast films, filtration membranes, and as an epoxy additive for composites, high-temperature paints and coatings, and adhesives. PES grades are used in the aerospace, automotive, electrical/electronics, medical-device, and food-handling industries.

In its role as a functional additive for epoxy composites, specific grades with hydroxyl (-OH) end groups are used. The end groups react with glycidyl groups on the epoxy matrix to form a cross-linked, interpenetrating polymer network (IPN).

Boosting Toughness of the Epoxy Composite

Even though the additive is typically used at low letdown ratios of 2-12 wt-%, it adds greater flexibility to the IPN, which in turn boosts the toughness of the epoxy composite.

SumikaExcel 5003P has a glass-transition temperature (Tg) of 230°C, which is higher than that typical of aerospace-grade epoxy resins (ranging from 120-200°C), and since it also has good stiffness and strength, it improves impact and crack resistance without compromising other thermo-mechanical properties.

Especially important for aerospace applications, it does all this without affecting FST or the ability to mold and hold very-tight tolerances. Although it is most commonly used with high-performance carbon fiber-reinforced epoxy composites, it is equally effective in glass- or basalt-reinforced epoxy composites too.